The present invention generally relates to excavating apparatus and, in a preferred embodiment thereof, more particularly provides an excavating adapter/tooth point assembly in which the tooth point is retained on a nose portion of the adapter for limited rocking motion relative thereto while a curved rear end surface area of the tooth point slidingly bears against a complementarily curved front surface area of a base portion of the adapter.
Large excavating buckets, dippers and the like are typically provided with a series of earth-cutting teeth which are each formed from two primary partsxe2x80x94a relatively large adapter, and a relatively small replaceable tooth point. The adapter has a base portion which is connectable to the forward lower lip of the bucket, and a tapered nose portion onto which the tooth point is removably secured, with the tapered adapter nose being received in an interior pocket portion of the point, by a suitable connecting pin or other connecting structure. Compared to that of the adapter, the useful life of the point is rather shortxe2x80x94the adapter typically lasting through five or more point replacements until the tremendous earth forces and abrasion to which the adapter is subjected necessitates its replacement.
AS conventionally designed, adapter/tooth point assemblies of this type are configured in a manner such that the adapter nose has a tapered configuration and is snugly and complementarily received in a tapered interior pocket portion of the tooth point in a manner limiting vertical rocking movement of the point relative to the adapter during excavating operations. While this snug tapered interfit between the adapter nose and a replacement tooth point captively retained thereon has been a long-accepted design feature in conventional adapter/tooth point assemblies, it has at least one well known disadvantage arising from this purposely snug fit between the tooth point and the adapter nose.
Specifically, after the assembly has been used in excavation tasks, the tremendous front-to-rear loads imposed on the tooth point tends to rearwardly drive it along the tapered adapter nose to an extent elastically deforming the tooth point side walls in lateral directions which, in turn, tends to firmly clamp the tooth point onto the adapter nose to an extent which often renders the subsequent task of removing the worn point from the adapter nose an inordinately difficult one.
In view of this it can be seen that a need exists for an adapter/tooth point assembly in which this problem is eliminated or at least substantially reduced. It is to this need that the present invention is primarily directed.
In carrying out principles of the present invention, in accordance with a preferred embodiment thereof, specially designed excavating apparatus is provided that comprises an adapter illustratively securable to a front edge portion of an excavating lip structure, a wear member representatively in the form of a replaceable tooth point, and a connection structure which is representatively in the form of a connector pin.
The adapter has a base with a curved front surface, and a nose projecting forwardly from the curved front surface. The wear member has a curved rear surface through which a pocket area forwardly extends, the pocket area being configured to removably receive and laterally envelop the adapter nose, and the curvature of the rear wear member surface being complementary to that of the front surface of the adapter base. Preferably, the curved front surface of the adapter base has a forwardly convex curvature, the curved rear surface of the wear member has a forwardly concave curvature, and the curved front adapter base surface slidingly engages substantially all of the complementarily curved rear wear member surface. When the adapter nose is placed in the wear member pocket area, the connector structure is inserted through aligned openings in the adapter nose and wear member to releasably retain the wear member on the adapter.
According to a key feature of the present invention, when the wear member is operatively mounted on the adapter, and the curved rear wear member surface is slidingly and complementarily engaged with the curved front surface of the adapter base, the wear member is permitted to pivot relative to the adapter through a limited arc (generally centered about an axis rearwardly offset from the connector structure) in a manner causing the curved wear member rear surface to slide along the curved adapter base front surface. In this manner, reactive loads created by rearwardly directed operating forces on the wear member are desirably shifted to the curved adapter base surface as opposed to being positioned more forwardly on the adapter nose.
Representatively, the adapter nose has a stabilizing tip portion with a front end surface that engages an inner end surface of the wear member pocket area, and a lateral clearance area is defined within the pocket area around the adapter nose therein. This clearance area causes a portion of the stabilizing tip portion to act as an abutment surface that limits the pivotal movement of the wear member relative to the adapter. The clearance area also prevents the wear member from being tightly wedged on the adapter nose, thereby facilitating removal of the wear member from the adapter nose.
According to another feature of the invention, the wear member has a pair of opposite outer side walls which extend rearwardly past the curved rear surface of the wear member and define abrasion shield structures that protectively overlie opposite side surface portions of the adapter base.
Illustratively, the wear member has a pair of opposite first and second outer side walls through which an aligned pair of first and second connection openings extend into the pocket area, the adapter nose has a third connection opening extending therethrough in alignment with the first and second connection openings, and the connection structure extends through the first, second and third connection openings. Representatively, the connection structure extends along an axis parallel to and spaced forwardly apart from the axis about which the wear member is pivotable relative to the adapter, the first and second connection openings have non-circular shapes and have curvatures generally parallel to the curvature of curved front adapter base surface, and the third connection opening has a circular cross-section.